1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1989, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 __SCCSID("@(#)nlist.c 8.1 (Berkeley) 6/4/93"); 34 #include "namespace.h" 35 #include <sys/param.h> 36 #include <sys/mman.h> 37 #include <sys/stat.h> 38 #include <sys/file.h> 39 #include <arpa/inet.h> 40 41 #include <errno.h> 42 #include <a.out.h> 43 #include <stdio.h> 44 #include <string.h> 45 #include <unistd.h> 46 #include "un-namespace.h" 47 48 #include <machine/elf.h> 49 #include <elf-hints.h> 50 51 int __fdnlist(int, struct nlist *); 52 int __elf_fdnlist(int, struct nlist *); 53 int __elf_is_okay__(Elf_Ehdr *); 54 55 int 56 nlist(const char *name, struct nlist *list) 57 { 58 int fd, n; 59 60 fd = _open(name, O_RDONLY | O_CLOEXEC, 0); 61 if (fd < 0) 62 return (-1); 63 n = __fdnlist(fd, list); 64 (void)_close(fd); 65 return (n); 66 } 67 68 static struct nlist_handlers { 69 int (*fn)(int fd, struct nlist *list); 70 } nlist_fn[] = { 71 { __elf_fdnlist }, 72 }; 73 74 int 75 __fdnlist(int fd, struct nlist *list) 76 { 77 int n = -1; 78 unsigned int i; 79 80 for (i = 0; i < nitems(nlist_fn); i++) { 81 n = (nlist_fn[i].fn)(fd, list); 82 if (n != -1) 83 break; 84 } 85 return (n); 86 } 87 88 #define ISLAST(p) (p->n_un.n_name == 0 || p->n_un.n_name[0] == 0) 89 90 static void elf_sym_to_nlist(struct nlist *, Elf_Sym *, Elf_Shdr *, int); 91 92 /* 93 * __elf_is_okay__ - Determine if ehdr really 94 * is ELF and valid for the target platform. 95 * 96 * WARNING: This is NOT an ELF ABI function and 97 * as such its use should be restricted. 98 */ 99 int 100 __elf_is_okay__(Elf_Ehdr *ehdr) 101 { 102 int retval = 0; 103 /* 104 * We need to check magic, class size, endianess, 105 * and version before we look at the rest of the 106 * Elf_Ehdr structure. These few elements are 107 * represented in a machine independent fashion. 108 */ 109 if (IS_ELF(*ehdr) && 110 ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS && 111 ehdr->e_ident[EI_DATA] == ELF_TARG_DATA && 112 ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) { 113 114 /* Now check the machine dependant header */ 115 if (ehdr->e_machine == ELF_TARG_MACH && 116 ehdr->e_version == ELF_TARG_VER) 117 retval = 1; 118 } 119 return retval; 120 } 121 122 int 123 __elf_fdnlist(int fd, struct nlist *list) 124 { 125 struct nlist *p; 126 Elf_Off symoff = 0, symstroff = 0; 127 Elf_Size symsize = 0, symstrsize = 0; 128 Elf_Ssize cc, i; 129 int nent = -1; 130 int errsave; 131 Elf_Sym sbuf[1024]; 132 Elf_Sym *s; 133 Elf_Ehdr ehdr; 134 char *strtab = NULL; 135 Elf_Shdr *shdr = NULL; 136 Elf_Size shdr_size; 137 void *base; 138 struct stat st; 139 140 /* Make sure obj is OK */ 141 if (lseek(fd, (off_t)0, SEEK_SET) == -1 || 142 _read(fd, &ehdr, sizeof(Elf_Ehdr)) != sizeof(Elf_Ehdr) || 143 !__elf_is_okay__(&ehdr) || 144 _fstat(fd, &st) < 0) 145 return (-1); 146 147 /* calculate section header table size */ 148 shdr_size = ehdr.e_shentsize * ehdr.e_shnum; 149 150 /* Make sure it's not too big to mmap */ 151 if (shdr_size > SIZE_T_MAX) { 152 errno = EFBIG; 153 return (-1); 154 } 155 156 /* mmap section header table */ 157 base = mmap(NULL, (size_t)shdr_size, PROT_READ, MAP_PRIVATE, fd, 158 (off_t)ehdr.e_shoff); 159 if (base == MAP_FAILED) 160 return (-1); 161 shdr = (Elf_Shdr *)base; 162 163 /* 164 * Find the symbol table entry and it's corresponding 165 * string table entry. Version 1.1 of the ABI states 166 * that there is only one symbol table but that this 167 * could change in the future. 168 */ 169 for (i = 0; i < ehdr.e_shnum; i++) { 170 if (shdr[i].sh_type == SHT_SYMTAB) { 171 symoff = shdr[i].sh_offset; 172 symsize = shdr[i].sh_size; 173 symstroff = shdr[shdr[i].sh_link].sh_offset; 174 symstrsize = shdr[shdr[i].sh_link].sh_size; 175 break; 176 } 177 } 178 179 /* Check for files too large to mmap. */ 180 if (symstrsize > SIZE_T_MAX) { 181 errno = EFBIG; 182 goto done; 183 } 184 /* 185 * Map string table into our address space. This gives us 186 * an easy way to randomly access all the strings, without 187 * making the memory allocation permanent as with malloc/free 188 * (i.e., munmap will return it to the system). 189 */ 190 base = mmap(NULL, (size_t)symstrsize, PROT_READ, MAP_PRIVATE, fd, 191 (off_t)symstroff); 192 if (base == MAP_FAILED) 193 goto done; 194 strtab = (char *)base; 195 196 /* 197 * clean out any left-over information for all valid entries. 198 * Type and value defined to be 0 if not found; historical 199 * versions cleared other and desc as well. Also figure out 200 * the largest string length so don't read any more of the 201 * string table than we have to. 202 * 203 * XXX clearing anything other than n_type and n_value violates 204 * the semantics given in the man page. 205 */ 206 nent = 0; 207 for (p = list; !ISLAST(p); ++p) { 208 p->n_type = 0; 209 p->n_other = 0; 210 p->n_desc = 0; 211 p->n_value = 0; 212 ++nent; 213 } 214 215 /* Don't process any further if object is stripped. */ 216 if (symoff == 0) 217 goto done; 218 219 if (lseek(fd, (off_t) symoff, SEEK_SET) == -1) { 220 nent = -1; 221 goto done; 222 } 223 224 while (symsize > 0 && nent > 0) { 225 cc = MIN(symsize, sizeof(sbuf)); 226 if (_read(fd, sbuf, cc) != cc) 227 break; 228 symsize -= cc; 229 for (s = sbuf; cc > 0 && nent > 0; ++s, cc -= sizeof(*s)) { 230 char *name; 231 struct nlist *p; 232 233 name = strtab + s->st_name; 234 if (name[0] == '\0') 235 continue; 236 for (p = list; !ISLAST(p); p++) { 237 if ((p->n_un.n_name[0] == '_' && 238 strcmp(name, p->n_un.n_name+1) == 0) 239 || strcmp(name, p->n_un.n_name) == 0) { 240 elf_sym_to_nlist(p, s, shdr, 241 ehdr.e_shnum); 242 if (--nent <= 0) 243 break; 244 } 245 } 246 } 247 } 248 done: 249 errsave = errno; 250 if (strtab != NULL) 251 munmap(strtab, symstrsize); 252 if (shdr != NULL) 253 munmap(shdr, shdr_size); 254 errno = errsave; 255 return (nent); 256 } 257 258 /* 259 * Convert an Elf_Sym into an nlist structure. This fills in only the 260 * n_value and n_type members. 261 */ 262 static void 263 elf_sym_to_nlist(struct nlist *nl, Elf_Sym *s, Elf_Shdr *shdr, int shnum) 264 { 265 nl->n_value = s->st_value; 266 267 switch (s->st_shndx) { 268 case SHN_UNDEF: 269 case SHN_COMMON: 270 nl->n_type = N_UNDF; 271 break; 272 case SHN_ABS: 273 nl->n_type = ELF_ST_TYPE(s->st_info) == STT_FILE ? 274 N_FN : N_ABS; 275 break; 276 default: 277 if (s->st_shndx >= shnum) 278 nl->n_type = N_UNDF; 279 else { 280 Elf_Shdr *sh = shdr + s->st_shndx; 281 282 nl->n_type = sh->sh_type == SHT_PROGBITS ? 283 (sh->sh_flags & SHF_WRITE ? N_DATA : N_TEXT) : 284 (sh->sh_type == SHT_NOBITS ? N_BSS : N_UNDF); 285 } 286 break; 287 } 288 289 if (ELF_ST_BIND(s->st_info) == STB_GLOBAL || 290 ELF_ST_BIND(s->st_info) == STB_WEAK) 291 nl->n_type |= N_EXT; 292 } 293